I haven't tried it yet, but I think the fact that there are LESS ingredients than many salsas seems on track. Here's the post I found online:

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Pretty simple, once you get the hang of it

1 can of chioptle chilies in adobo sauce (found in latin section of market)
1 medium can of diced tomatoes (drained well)
6 japan chiles (these are dried red skinny long chiles) stems removed

Put 3 chipotle chilies in a blender (can usually has 6 chilies)
Put your drained tomatoes in the blender also
Put the japan chilies in the oven under the broiler and let them char (this will get smoky and smell bad, so be careful to ventillate your oven and kitchen well)
Put the charred chiles in the blender
Once all ingredients are in the blender, mix well until all is blended into a puree